1. Field of the Invention
This invention relates to an information transmission system which transmits information, such as image information or audio information recorded as a cluster of information blocks, in response to information transmission requests from a large number of external machines. The invention also relates to information recording system of the external machines for recording the received information, and in particular relates to an information transmission system appropriate for shortening the time required from the issuing of a transmission request to the information transmission end to the transmitting of the information in response to information transmission requests, these requests coming from different external machines, and occurring at the same time, and from information recording devices associated with the information transmission system.
2. Description of the Related Art
Devices that can transmit information such as picture information and audio information include video tape recorders (VTRs), optical disk units, magnetic disk units, semiconductor memories, etc. The related art of these storage devices is described in IC Memory Card Guidelines Vet.4.1 (1991.9) published by Nihon Densikikaikogyo Shinko Kyokai and Home VTR Nyumon (or Introduction to Home VTR) (1971.10), published by Corona. With the storage devices in the related art, information can be written onto storage media and the written information can be read and transmitted externally. Likewise, at the receiving parties, the devices for recording the received information include video tape recorders (VTRs), optical disk units, magnetic disk units, semiconductor memories, etc. In the information recording devices, an area in which information can be recorded is reserved corresponding to the received information amount and the information is sequentially recorded starting at the beginning of the area.
By the way, it is anticipated that a system which holds information such as picture information, music information, and game software information as a database, and transmits necessary information to a plurality of external machines will come into demand, with high speed operation and large capacity of information transmission networks. Such a system, which transmits information, such as picture information, music information, and game software information to a plurality of external machines, requires a reception circuit for receiving information transmission requests from the external machines and a plurality of transmission circuits. Further, when a large number of information transmission requests occur for the same information at the same time, serial operation, in which information transmission responsive to the first transmission request is completed and then information is transmitted in response to the second transmission request, would mean that each external machine (the user of the external machine) has to wait for the length of time between the instant at which an information transmission request is issued and the instant at which information transmission is started. This wait time depends on the number of machines requesting information transmission, and so it is impossible to schedule the time interval. This problem becomes remarkable, particularly when transmission of picture information of a movie or the like, having an enormous information amount, is requested.
However, the storage devices do not generally comprise a plurality of reception circuits or a plurality of transmission circuits, and their control method is not explicit. Particularly, if a second information transmission request occurs while video information or audio information is being reproduced in response to a first information transmission request, the function of receiving the second request is not provided. Even if the storage devices have the capability of receiving a plurality of information transmission requests, when a second information transmission request occurs while information is being sent (video information or audio information is being reproduced) in response to a first information transmission request, it is considered that information transmission processing is performed in sequence in such a manner that information transmission responsive to the first transmission request is completed and then information is transmitted in response to the second transmission request. The information is always sent starting at the beginning, and not at an intermediate point of the information.